[lib] Use staging Blob URL for dev

Summary: For dev builds, we should use staging blob service URL. We do so for backup and reports already.

Test Plan: Console.log in dev build shows staging URL.

Reviewers: kamil, michal, atul

Reviewed By: kamil

Subscribers: ashoat, tomek, wyilio

Differential Revision: https://phab.comm.dev/D9615